The object is to improve the hydraulic performance of the axial-flow pump and find out the main geometric parameters that affect the performance of axial-flow pump. Based on the L9(34) orthogonal experiment, number of blades, airfoil seating angle, hub ratio, the distance between the blade and guide vane were selected as test factors, and each experimental factor corresponded to three levels. Using orthogonal test method, the head, efficiency, shaft power and pressure pulsation were taken as the evaluation indexes. According to the results of intuitive analysis and range analysis, the best experimental scheme was determined by comprehensive frequency analysis. The results showed that hub ratio had the greatest influence on the four test evaluation indexes and the distance between blade and guide vane had the least effect. Under the optimum test plan, the flow regime was better, the whirlpool on the back of guide vane almost disappeared and the streamline on the blade surface distributed evenly. After optimization, the high pressure area of the blade surface disappeared basically, and the pressure distribution was more uniform, and the optimization effect was better. Compared with the original model，the optimized model of axial-flow pump in the flow and head satisfied requirement for module at the same time, under the new design flow, efficiency was increased from 74.33% to 78.59%, which was increased by 5.7%;shaft power was decreased from 20.54kW to 20.29kW, which was fallen by 1.21%;pressure pulsation coefficient absolute value was decreased from 0.344 to 0.310, which was reduced by 11%. Four evaluation indexes were achieved and the optimized model of axial-flow pump had a wide range of efficient area and the feasibility of comprehensive frequency analysis method in multi-objective orthogonal optimization was verified.